SYRACUSE, NY -- A Fulton man sexually abused four boys and produced pornography of three, then attempted to blame a 12-year-old, according to a plea agreement filed today in federal court.

Efrain J. Rosa, 38, of 30 W. 11th St., pleaded guilty to three counts of producing child pornography and one count of witness tampering, according to Assistant U.S. Attorney Lisa Fletcher. He faces up to 30 years each in federal prison for the pornography and witness tampering charges. He must register as a sex offender.

Rosa possessed several thousand images and more than 100 videos of child pornography on his computer, according to the plea agreement. Images of his victims were sorted by first names.

Rosa was questioned Sept. 26, 2007, after two women told authorities their young boys, ages 9 and 11, were sexually abused by a neighbor called "J," both Rosa's nickname and middle initial, court papers stated.

Questioned by investigators, Rosa admitted he also abused two other boys, ages 4 and 8, prosecutors said.

Rosa was arrested on child pornography charges Oct. 5, 2007. In recorded calls from jail, he coerced a 12-year-old into falsely claiming the child produced the images, according to the plea.

He told the child that by admitting to the crimes, the child would only get counseling and Rosa would be released from jail so they could be a family again, according to a transcript of one phone call.

The child sent at least two letters, addressed to Rosa, falsely claiming responsibility, according to prosecutors.